The present invention provides a semiconductor device having such a structure formed by sequentially laminating a lower barrier layer composed of lattice-relaxed AlxGa1-xN (0≦x≦1), a channel layer composed of InyGa1-yN (0≦y≦1) with compressive strain and a contact layer composed of AlzGa1-zN (0≦z≦1), wherein a two-dimensional electron gas is produced in the vicinity of an interface of said InyGa1-yN channel layer with said AlzGa1-zN contact layer; a gate electrode is formed so as to be embedded in the recessed portion with intervention of an insulating film, which recessed portion is formed by removing a part of said AlzGa1-zN contact layer by etching it away until said InyGa1-yN channel layer is exposed; and, ohmic electrodes are formed on the AlzGa1-zN contact layer. Thus, the semiconductor device has superior uniformity and reproducibility of the threshold voltage while maintaining a low gate leakage current, and is also applicable to the enhancement mode type.